Contamination in the household of monkeypox-infected individuals

By Bhavana KunkalikarAug 24 2022Reviewed by Aimee Molineux

In a recent study published in the Morbidity and Mortality Weekly Report journal, researchers reported high-contact surface and object contamination in a household of individuals infected with the monkeypox virus.

In May 2022, two travel-associated monkeypox cases confirmed by a real-time polymerase chain reaction (PCR) were reported by the Salt Lake County Health Department to the Utah Department of Health and Human Services (UDHHS). The persons with monkeypox, patients A and B resided together without any other housemates.   

Case findings

The patients experienced prodromal symptoms such as body aches and fatigue. The patients reported that eight days post-symptom onset, patient A suffered from penile lesions. These lesions then spread to the hands, legs, lips, scalp, and chest by day 10. Patient B reported prodromal symptoms eight days after the symptoms onset of patient A. Patient B reported a lesion on the foot which further spread to the finger and leg by day 11. Although the patients displayed lesions in several anatomic regions, the overall number of lesions observed was small, with their appearance ranging from ulcerated or pimple-like, to either well-circumscribed or centrally umbilicated. The duration between onset of symptoms to resolution was approximately 30 and 22 days for patients A and B, respectively.

The manifestation and degree of contamination of household objects touched by monkeypox patients were assessed by swabbing objects from the patients’ homes. The patients identified the high-contact surfaces and objects for sampling. The patients also defined the disinfection and cleaning activities that were performed in the home during the course of the infection. The patients had self-isolated at home for 20 days before their home was sampled. The temperature in the home ranged between 69°F (20.6°C) to 75°F (23.9°C) throughout their period of isolation.

The UDHHS personnel conducted targeted environmental sampling wherein specimens were collected from 30 objects from nine areas of the patients’ home. These samples were then transported to the Utah Public Health Laboratory, where the samples were processed and analyzed with nonvariola Orthopoxvirus and West African Monkeypox virus–specific real-time PCR assays. The viral culture was analyzed only after the qualitative PCR result tested positive.    

Results

The study results showed that 70% of the 30 specimens tested showed positive real-time PCR. This included all three porous materials such as blankets and cloth furniture, one of two mixed surface types such as chairs, and 68% non-porous surfaces such as switches and handles. None of the specimens resulted in a positive viral culture result. During the isolation period, the patients reported showering one or two times every day, laundering clothing and bedding weekly, and home cleaning performed routinely.

The team detected the monkeypox virus deoxyribonucleic acid (DNA) on several objects and surfaces, indicating the presence of some magnitude of contamination in the household environment. However, the inability to detect any viable virus suggested that viral viability could have decayed over time or via environmental or chemical inactivation. While both the symptomatic patients were isolated in their home for over three weeks, the cleaning and disinfection practices might potentially have limited the contamination level in the home.

Overall, the study highlighted that individuals living with or visiting the homes of monkeypox patients must follow appropriate precautions against potential exposure and transmission by using facemasks, avoiding direct contact with contaminated surfaces, and maintaining proper hygiene.